# Debye_number

plasmapy.formulary.dimensionless.Debye_number(T_e: Unit('K'), n_e: Unit('1 / m3'))

Return the number of electrons within a sphere with a radius of the Debye length.

Aliases:

Parameters
Raises
Warns

– If units are not provided, SI units are assumed.

Returns

N_D – Number of electrons within a sphere with a radius of the Debye length.

Return type

Notes

The Debye number is the number of electrons contained within a sphere with a radius of a Debye length and is given by

$N_D = \frac{4π}{3} n_e λ_D^3$

The Debye number is also known as the plasma parameter.

Collective behavior requires $$N_D ≫ 1$$.

Examples

>>> from astropy import units as u
>>> Debye_number(5e6*u.K, 5e9*u.cm**-3)
<Quantity 2.17658...e+08>